The use of closure devices for closure of containers, including plastic bags, is generally well known. The closure device and the associated container are formed, typically, from thermoplastic materials. The manufacture of closure devices by extrusion is generally known to those skilled in the art of closure devices. Closure devices are generally either extruded and then attached to the container or integrally formed with the container.
These devices are resealable, which allows the container to be reused. In general, a closure device provides relatively high resistance to opening from interior the container while rendering the container relatively easy to open from the exterior. However, in certain circumstances, it may be desirable for a closure device to provide high resistance to opening from the exterior as well.
The interior of the container may be under relatively high pressure or relatively low pressure because of varying internal contents and external environments. To provide the appropriate resistance to opening from the interior or exterior and to keep the container closed, closure devices typically use a combination of interlocking hooks. In some closure devices, the contact surfaces between the interlocking hooks provide the primary seal for the container. One difficulty with this design may be providing a secure closure and an air tight or leak proof seal while maintaining a closure that is easy to occlude as well as open from the exterior. On occasion it may occur that the interlocking hooks may not contact each other, yet remain occluded, because of slight variations in the hooks or because the conditions under which the closure device is used cause the hooks to not contact each other as shown in FIG. 33. If, while in an occluded position, the interlocking hooks are not intimately mated, the closure device may not adequately provide an air tight or leak proof seal.